Steel spring insulator

ABSTRACT

A steel spring insulator, to enable machines or sets of machinery, particularly fans, ventilators, blowers etc., to be installed in such a way that they will be insulated from vibrations and protected from sound conducted through solids, the said insulator comprising a lower portion firmly affixed to the bearing surface of a foundation or a supporting structure, and an upper portion affixed underneath the base of the machine or set of machinery or underneath a bearer thereof, at least one steel helical compression spring being provided between the said two portions and being surrounded by the upper and/or lower portion on all sides and with ample clearance, at least one connecting element being provided which interconnects the upper and the lower portion and keeps the compression spring in a prestressed state, wherein the connecting element consists of at least one flexible traction means which is affixed by one end portion to the lower part and by the other end portion to the upper part and of which the length is such that when the insulator is not subjected to a load the traction means is loaded and the compression spring is slightly prestressed, said traction means being relieved of its load and hanging loosely not later than when the insulator has reached its minimum permissible loading.

Riintgen 1 June 4, 1974 1 1 STEEL SPRING INSULATOR [751 lnventor: Peter Riintgen, Giessen, Germany 173] Assignee: Isoliertechnik Horst Grassmann,

Frankfurt/Main, Germany 1 Filed: Apr.2l,l97l

211 Appl. No; 135,946

[301 Foreign Application Priority Data Apr, 22, 1970 Germany 2019348 [521 [1.5. CI. 248/20 [51] Int. Cl Fl6j 15/00 [58] Field of Search.....'..... 248/1854, 350, 358 AA, 248/399; 287/86 [561 References Cited UNITED STATES PATENTS 944,461 12/1909 Olander 248/1884 1,200,134 10/1916 Reischmann... 248/399 X 1,319,949 10/1919 Curran et al- 248/350 X 1,683,885 9/1928 Gunn 248/350 1.817.255 8/1931 Hawley 287/86 2.664257 12/1953 McNally 248/350 UX 2,717,629 9/1955 Badhorn 248/399 X 2,908,456 10/1959 Gertel 248/350 UX 3.424.413 1/1969 MAI/I4 IIIIII/III/I/I/llV/IIII Primary E.\aminerWilliam H. Schultz Attorney, Agent, or FirmMichael S. Striker 1 5 7 ABSTRACT A steel spring insulator, to enable machines or sets of machinery, particularly fans, ventilators, blowers etc., to be installed in such a way that they will be insulated from vibrations and protected from sound conducted through solids, the said insulator comprising a lower portion firmly affixed to the bearing surface of a foundation or a supporting structure, and an upper portion affixed underneath the base of the machine or set of machinery or underneath a bearer thereof, at least one steel helical compression spring being provided between the said two portions and being surrounded by the upper and/or lower portion on all sides and with ample clearance, at least one connecting element being provided which interconnects the upper and the lower portion and keeps the compression spring in a prestressed state, wherein the connecting element consists of at least one flexible traction means which is affixed by one end portion to the lower part and by the other end portion to the upper part and of which the length is such that when the insulator is not subjected to a load the traction means is loaded and the compression spring is slightly prestressed, said traction means being relieved of its load and hanging loosely not later than when the insulator has reached its minimum permissible loading.

15 Claims, 2 Drawing Figures STEEL SPRING INSULATOR BACKGROUND OF THE INVENTION This invention relates to a steel spring insulator, to enable machines or sets of machinery, particularly fans, ventilators, blowers etc., to be installed in such a way that they will be insulated from vibrations and protected from sound conducted through solids, the said insulator comprising a lower portion firmly affixed to the bearing surface of a foundation or a supporting structure, and an upper portion affixed underneath the base of the machine or set of machinery or underneath a bearer thereof, at least one steel helical compression spring being provided between the said two portions and being surrounded by the upper and/or lower portion on all sides and with ample clearance, at least one connecting element being provided which interconnects the upper and the lower portion and keeps the compression spring in a prestressed state.

Steel spring insulators of this kind can be used, as a general principle, in all machines or sets of machinery which are to be installed in such a way as to be insulated from vibrations and protected from sound conducted through solids, such as compressors, pumps, machine tools etc. Vibration or sound conduction occurs with widely varying frequencies in a considerable variety of machines and installations. To ensure optimum vibration damping and insulation efficiency it is essential that the natural frequencies of the insulators should be far below the frequencies of the vibrations to be combated. Forthis reason steel spring insulators are suitable first and foremost for the erection of machines or sets of machinery in such a Way as to insulate them from vibrations and protect them from sound conducted through solids when the vibrations occur in the said machinery at particularly low frequencies. This is the case, for example, with large ventilating equipment for theatres, concert halls, cinemas etc., these fans being operated at a low speed of rotation in order to reduce noise. Fans of this type can only be insulated from vibrations and protected from sound conduction by the aid of steel springinsulators, of which the compression springs are very soft. These soft compression springs are subjected to considerable compression by the-load placed on them by the machinery. A soft spring installation of this kind is very sensitive to fluctuations in the load, the spring travel strokes occurring in the case of the compression spring being comparatively long.

In a known steel spring insulator of the type mentioned at the beginning the upper and the lower part are substantially pot-shaped and of different diameters. The pot-shaped upper part and the similarly constructed lower part face towards each other by their openings and overlap telescopically over a part of their axial length. In this system the upper part embraces the upper edge of the lower part, in order to prevent the ingress of dirt and moisture into the internal space formed between the two parts. The said space contains the helical compression spring which rests bothagainst the inside of the upper part and against that of the lower part. To ensure that the steel spring insulator assembly will not come apart, particularly during transport or in the course of the erection operations, the interior of the upper part contains a screw which takes a coaxial course to the longitudinal central axis of the steel spring insulator and which passes through a boring in the lower part of the latter. The head of the screw is situated in a free space which is provided in the lower part and which is situated on that side of the base of the latter which faces away from the upper part. To enable the said space to be formed the floor of the lower part is given the shape of a truncated cone, and the boring through which the shank of the screw passes is provided in the zone of the central longitudinal axis, in the upper end face of the aforementioned frustum-shaped portion of the floor. The internal diameter of the said boring is only slightly greater than the external diameter of the shank of the screw, so that the latter can perform, inside the boring, an axial movement corresponding to the relative movements of the upper and the lower part. The internal diameter of the boring, however, is smaller than the external diameter of the head of the screw, so that the latter will not go through the boring and the screw has to be pushed through the boring in the floor of the lower side, when the steel spring insulator system is being assembled, and can only then be firmly screwed into the likewise frustum-shaped floor of the upper part. The length of the screw is such that even when the steel spring insulator is fully relieved the compression spring is still slightly prestressed. This operation interconnects the upper and the lower part and prevents the steel spring insulator system from coming apart.

This known steelspring insulatr is nevertheless subject to the drawback of being still liable to transmit vibrations, which defeat its actual purpose. The main rea son for this is that it is not merely via the compression spring, with its damping function, that the upper and the lower part are interconnected, a vibrationtransmitting connection between the said two parts also prevailing via the screw and via the internal wall of its guide bore in the lower part. It is true that this vibration-transmitting connection is theoretically nonexistent, owing to the slight clearance with which the screw is held in the boring of the lower part. In practice, however, it has been found that the upper and the lower part of the steel spring insulator frequently tilt, in which case the shank of the screw and the internal surface of the boring in the floor of the lower part come in contact with each other, so that vibrations are transmitted from the upper part, via the screw and the internal wall of the boring, to the lower part. Very slight tilting of the upper part in relation to the lower part suffices to cause the screw to contact the internal wall of the boring, because the lever arm formed by the screw is very considerable and the clearance between the shank of the screw and the internal wall of the boring is relatively slight. ln steel spring insulators of this type the slight tilting mentioned is unavoidable, because the vibrations act not only in an exactly vertical but also in a horizontal direction, as well as obliquely, on the upper part of the insulator, causing it to perform corresponding movements in respect of the lower part. The screw thus forms a vibration-transmitting bridge and detracts considerably from the insulating effect of the steel spring insulator. In addition, a certain tilting of the upper part in relation to the lower part also results in contact between these two parts themselves, owing to the limited radial distance between the internal wall of the upper part and the external wall of the lower part, so that vibrations can be transmitted from the upper to the lower part via this point of contact likewise. in many cases, therefore, the upper and the lower part form a direct bridge, by which the insulating efficiency of the steel spring insulator is seriously reduced.

A further major drawback of the known steel spring insulator resides in the fact that the upper and the lower part are liable to tilt to such an extent as to cause jamming, as a result of which the necessary free relative motion between the two parts is completely nullified. In the known construction jamming of this kind may occur above all between the shank of the screw and the internal wall of the boring in the base of the lower part. This jamming between the shank of the screw and the internal wall of the boring in the base of the lower part is due to the comparatively limited clearance between the said shank and the said internal surface. For constructional reasons, and particularly owing to the fact that the head of the screw must not pass through the boring, it is not possible to increase the clearance between the shank of the screw and the surface of the boring in such a way as to enable jamming at this point to be avoided altogether.

The damger of jamming between the upper and the lower part is naturally the greater, the softer the compression spring or the longer the spring travel occurring during operation is made as a result of the manner in which the compression spring in question is designed. One reason why the spring travel in the known construction is relatively slight is that the rigid screw in the free space underneath the frustum-shaped portion of the base of the lower part can only be given just enough room, for constructional reasons, to enable it to move in an axial distance through a distance of up to about mm at the most. To prolong this free space as required would involve considerable difficulties from the point of view of the manufacturing process, particularly if the lower part consisted of a casting. It is true that a free spaceof greater length in the axial direction would be practicablein the case of a welded construction, or if the lower part were turned from the solid, but this wouldinvolve up to about ten times the cost of the casting, which would naturally not be tenable from an economic point of view.

For the aforementioned reasons only a comparatively short spring travel, amounting to about 20 mm, can be provided in the case of the known type of construction. Short excursions of this kind have very undesirable ef fects, particularly in the case of vibrations with very low frequencies, because, under such circumstances satisfactory insulation calls for an excursion of 60 mm and more. For the aforementioned reasons, however, such long spring travel,'in the known steel spring insulator construction, proves impracticable. Consequently, steel spring insulators of the type described at the beginning and already known are not suitable for machines running at rotation speeds of below 500 rpm. In such cases steel spring insulators are required which are provided with special upper and lower parts of the welded type, of which the cost, as already mentioned, is far higher than that of cast upper or lower parts. For particularly great strokes and heavy loads, use is also made of steel spring insulators with a number of compression springs and connecting elements of the welded housing type. but these systems suffer, mutatis mutandis, from the disadvantages already mentioned.

SUMMARY OF THE INVENTION It is the object of the invention to provide a steel spring insulator which will be free of the drawbacks discussed in the foregoing and of which the vibrationand sound-resisting properties will prove more satisfactory than in the known system and which, above all, will be suitable for the insulation and damping of particularly low frequencies.

To attain this object the present invention provides a steel spring insulator, to enable machines or sets of machinery, particularly fans, ventilators, blowers etc., to be installed in such a way that they will be insulated from vibrations and protected from sound conducted through solids, the said insulator comprising a lower portion firmly affixed to the bearing surface of a foundation or a supporting structure, and an upper portion affixed underneath the base of the machine or set of machinery or underneath a bearer thereof, at least one steel helical compression spring being provided between the said two portions and being surrounded by the upper and/or lower portion on all sides and with ample clearance, at least one connecting element being provided which interconnects the upper and the lower portion and keeps the compression spring in a prestressed state, wherein the connecting element consists of at least one flexible traction means which is affixed by one end portion to the lower part and by the other end portion to the upper part and'of which the length is such that when the insulator is not subjected to a load the traction means is loaded and the compression spring'is slightly prestressed, said traction means being relieved of its load and hanging loosely not later than when the insulator has reached its minimum permissible loading.

The use of a flexible traction means as a connecting element in place of the rigid screw employed in the known design ensures that the transmission of vibrations from the upper to the lower part of the steel spring insulator can no longer occur. Unlike the rigid screw which vibrates together with the upper part in the known system, a flexible traction means suspended with a certain amount of-sag cannot be set in vibration by the upper part in such a way as to enable the vibrations to be transmitted to the lower part The transmission of the vibrations to the lower part from the flexible, sagging traction means, resting loosely on the floor of the said lower part, is no longer possible, in contradistinction to the construction already known. The sole connection between the upper and the lower part, other than the compression spring serving as a damping element, is thus constructed on vibration-insulating lines, as a result of which the insulating effect of the steel spring insulator covered by the invention is considerably improved.

A further advantage of the steel spring insulator to which the invention relates resides in the fact that owing to the elimination of the screw and also of the boring in the base of the lower part, through which boring the screw in the known system-has to pass, no jamming can any longer occur between the upper and the lower part. Since jamming between the two parts can be reliably avoided at the other points likewise, by selecting the appropriate diameters for those of their respective portions which overlap each other telescopically, all jamming between the upper and the lower part of the steel spring insulator covered by the invention is avoided. This also applies when the spring travel of the compression spring is particularly great during operation, and likewise in cases in which considerable horizontal vibrations take place between the said two parts. The connecting element constructed as a flexible traction means automatically adapts itself to all these relative movements, so that the entire steel spring insulator to which the invention relates functions during operation in the manner of a steel spring without a housing, i.e., the upper and the lower parts are freely movable in respect of each other in all direction, and the connecting element betweenthem has no guiding properties.

The steel spring insulator covered by the invention therefore likewise renders it unnecessary to limit the excursion of the compression spring to a maximum of 20 mm. On the contrary: in the suggested construction the compression spring can be designed in accordance with the load occurring, in such a way that in the course of its operation it can cover a path of, for example, 60 mm and over. This has the advantage of providing a very soft spring characteristic, exerting an effective damping action in the case of all vibrations with very low rotation speeds. The steel spring insulator to which the invention relates thus makes it possible, for instance, to erect machines or sets of machinery in such a way that they are insulated from vibrations, even in the case of very low rotation speeds, e.g. only 250 r.p.m., with the correspondingly low vibration frequencies. ln contradistinction to the known construction, therefore, full use can be made of the effect of the compression springs, as the upper and the lower part of the insulator can be constructed with as ample a clearance as desired. In addition,- the steel spring insulator covered by the invention is far simpler in its construction, because the frustum-shaped base can be dispensed with, at all events where the lower part is concerned. Furthermore, the proposed insulator can be assembled more easily. This reduces the cost of production and thus enables it to be manufactured more economically. It can also be made to a more moderate over-all height than the known steel spring insulator, which in many cases is an essential requirement.

In a particularly advantageous embodiment of the invention, only one flexible traction means is associated with each helical compression spring and is approximately coaxial to the said spring, passing through its centre, the spring together with the traction means being surrounded on all sides, and with ample clearance, by the lower end and the upper part of the insulator. This provides the advantage that for each helical compression spring present between the upper and the lower part of the insulator only one flexible traction means is required and that an extremely reliable connection between the said two parts is nevertheless obtained by means of the said traction means. In addition, the traction means approximately coaxial with the helical compression spring and passing through the centre thereof, in this embodiment of the insulator, is situated inside the spring in such a way as to be protected on all sides, and occupies no additional space to one side of the spring, so that the upper and the lower part of the insulator can be made particularly small and compact. A further essential advantage of this method of arranging the traction means resides in the fact that the points of application for the force of the helical compression spring and that of the traction means are situated on one and the same axis, so that no undesirable tilting can take place between the upper and the lower part of the insulator. Furthermore, in this embodiment of the invention, both the helical compression spring and the traction means passing through its centre are effectively protected by the upper and the lower part of the insulator, which surround these two components on all sides and with ample clearance, against extraneous mechanical stresses and also against the ingress of dirt.

Although in the majority of cases the steel spring insulator to which the invention relates is only provided with one helical compression spring and one connecting element, constructed as a flexible traction device and situated between the upper and the lower part, the invention extends to insulators of the kind comprising two or more helical compression springs between the said two parts, which are then interconnected by two or more flexible traction devices. In this latter case likewise, however, it is advisable for only one flexible traction means to be associated with each helical compression spring, the said traction device being approximately coaxial with the helical compression spring and passing through its centre.

In one suitable form of construction the traction means consists of a metal chain, preferably a welded chain with steel links. It is also possible, however, for the traction means to consist of a cable, preferably of steel. The aforementioned traction devices are particularly suitable for steel. spring insulators which are designed for high loads and of which the compression springs are consequently very strong. For this reason the traction device employed must itself be capable of standing up to heavy loads, since otherwise, with the compression spring not loaded, it would break as a result of the prestressing. The aforementioned traction devices, however, are particularly strong, resisting both permanent loads and high temperatures. A traction device of this kind, however, can never transmit pressures, as would be liable to occur, as a general principle, if the steel spring insulator were subjected to a force greater than the prestressing force of the compression spring, and if use were made of a screw such as that adopted in the known construction. In the known system this compressive stress, which would nullify the vibration-insulating effect of the compression spring, is avoided by means of a corresponding free space, to which, however, certain limits are set by constructional factors. The design to which the invention relates and its traction means mentioned in the foregoing necessitate no special free space, on the other hand, but hang loosely in the interior of the free space already provided, this being surrounded by the helical compression spring. The latter also applied to a traction means consisting of a cable, thread or chain of plastics which can likewise be employed according to an additional characteristic of the invention.

It is advisable for the traction means to be detachably affixed to the upper and/or the lower part. If the traction means is detachably affixed in this way it can be removed and replaced without difficulty, and the task of dismantling or assembling the steel spring insulator proves a simple one.

Altogether, it is desirable for the compression spring to rest against the upper and/or the lower part via a mounting and guiding ring made of a material constituting an insulant against sound conducted through solids, such as a ring made of plastics or rubber. A mounting and guiding ring of this kind proves an advantageous means of breaking the transmission of such sound from the upper part to the compression spring or from this latter to the lower part, so that the insulating effect of the steel spring insulator covered by the invention is improved still further. In addition, a mounting and guiding ring of this kind provides a reliable surface for the compression spring to rest against the upper or lower part, uneven places due to the manufacturing process being compensated at the same time. Again, a mounting and guiding ring of this kind is capable of securing the upper part and the compression spring, or the compression spring and the lower part, as the case may be, in their correct positions in a radial direction. The upper and the lower part of the spring insulator centre themselves solely via the compression spring. The latter must therefore be mounted in the lower part and in the upper part. This result, however, can also be achieved by means of appropriate attachments and recesses. In each of these embodiments of the invention it is possible, for example, for the compression spring to be gripped by its outer diameter in the lower part and by its inner diameter in the upper part.

In a preferred embodiment of the invention, that component of the insulator which is situated nearest to the compression spring as viewed in the radial direction, and preferably the lower part, comprises a widened portion, turned recess or the like, serving to increase the clearance provided all round between the compression spring and the component. A widened, turned or similar portion of this kind prevents the compression spring from making impact on the component in question, which would cause noise in operation. Furthermore a widened, turned or similar part of this kind enables the spring to oscillate over a considerable distance in the radial direction likewise, so that even considerable horizontal vibrations can be absorbed and damped, without the jamming or even damage, as well as acoustic bridges, such as are liable to occur in the known systems.

In many cases it is of advantage for the upper and/or lower part to be provided with a device enabling the bearing surfaces of the insulator to be adjusted in height. By the aid of a height-adjusting device of this kind on the steel spring insulators it is possible not only i to level out the machinesor sets of machinery in a simple manner but also to compensate even considerable gradients in the bearing surfaces of the foundations or supporting structures. A height-adjusting device of this kind, with an ample stroke, can be used with particular advantage and without difficulty in the steel spring insulator covered by the invention, because with this latter, in contradistinction to the known design, there is no reason to fear jamming of individual parts of the insulator. The fact is that in the known design the danger of jamming is considerably increased if a height adjusting device is adopted, because in this case the effective lever arm, from the base of the machine or installation as far as that part of the shank of the screw which is held in the boring of the lower part of the insulator, is considerably lengthened.

According to a further characteristic of the invention, at least the upper and/or the lower part may consist of an oil-, petroland acid-resisting synthetic material, characterized by considerable tenacity and resistance to abrasion. Plastics with these properties are to be found, for example, among the PVCs or polyethylenes.

BRIEF DESCRIPTION OF THE DRAWINGS Two embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which:

FIG. I is a vertical section of a steel spring insulator according to the invention, without height-adjusting device, and

FIG. 2 is a similar view of a steel spring insulator provided with a height-adjusting device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a steel spring insulator 1 which is pro vided with a pot-shaped upper part 2 and with a lower part 3 likewise substantially pot-shaped. The lower part 3 is provided with flange-like attachments 3a which serve to enable the lower part 3 to be affixed to a foundation 4. Securing screws 5 are used for this latter purpose and, in FIG. 1, are merely indicated by dot-anddash lines.

The upper part 2 and the lower part 3 face towards each other by their openings and overlap each other telescopically by their outer edge zones. They form one common internal space 6 containing a steel helical compression spring 7. The helical compression spring 7 rests both on the base of the lower part 3 and on that of the upper part 2. Between the base of the upper part 2 and the compression spring 7 is a mounting and guiding ring 8 consisting of a material, such as plastics or rubber, acting as an insulant against sound conducted through solids. The base of the pot-shaped upper part 2 is frustum-shaped in the zone of the longitudinal central axis. An attachment 2a of the shape of a truncated zone extends downwards. To this frustum-shaped attachment 2a is affixed a chain 9 permanently attached by its lower end portion to the base of the lower part 3 of the insulator. The chain 9 is coaxial with the helical compression spring 7 and passes through the center of this latter. As indicated by the arrow P in FIG. 1, the steel spring insulator l is shown in its loaded state, the

load emanating from a machine or set of machinery not shown in FIG. 1. Consequently, the helical compression spring 7 is compressed by a distance corresponding to the excursion caused in the spring by the load P, so that the chain 9 is relieved of load and hangs loosely.

The radial dimensions of the upper part 2, the lower part 3 and the helical compression spring 7 are adapted to one another, as may be clearly seen from FIG. 1, in such a way that a considerable radial clearance is provided between these separate parts, and this clearance can be made much greater than implied by the drawings. According to the particular purpose for which the steel spring insulator l is to be used, this clearance can be made either greater or smaller. The lower part 3 has a recess 3b produced by the turning process and providing a particularly ample distance between the said lower part 3 and the helical compression spring 7. The said helical compression spring 7 can thus oscillate to a comparatively considerable distance in the radial direction likewise, without making impact with the lower part 3. The turned recess 3b, however, does not extend as far as the base of the lower part 3 but terminates in the zone of the last turn of the compression spring 7. The said compression spring 7 is thus satisfactorily guided in the radial direction in the lower part 3, yet

without impeding the lateral deflection of the compression spring 7, as this movement in the main takes place solely in the upper and central portions of the length of the compression spring 7.

FIG. 2 shows a steel spring insulator 1 constructed substantially on the same lines as the steel spring insulator illustrated in FIG. 1. The steel spring insulator l in FIG. 2, however, differs from that shown in FIG. 1 in that in place of the chain 9 a cable 9a is used as the traction means interconnecting the upper part 2 and the lower part 3. Furthermore, the steel spring insulator l in the embodiment shown in FIG. 2 is provided with a height-adjusting device 10 which consists of a bolt 11, two hexagonal nuts 12 and 13 and a supporting disc 14. The bolt 11 is screwed by its lower end portion into the base of the upper part 2. Needless to say, the bolt 11 could also be connected with the upper part 2 by weld- The lower hexagonal nut 12 enables the height of the supporting disc 14 on the bolt 11 to be adjusted, the said disc being provided with a through-boring. The hexagonal nut 13 serves to secure the hexagonal nut 12, so that the height of the supporting disc 14 is firmly fixed, once the hexagonal nuts 12 and 13 have been tightened up. The base of the machine or set of machinery, which is not shown in FIG. 2, then rests on the upper side of the support disc 14, which side faces away from the upper and lower part 3 and 2 respectively of the steel spring insulator 1. In this system the stand'of the machine or installation or of a supporting beam will be situated between thesupporting disc 14 and the hexagonal nut 13, so that the said hexagonal nut 13 serves not only to secure the hexagonal nut 12 but also to secure the said machine stand.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The embodiments are therefore to be considered in all respects as illustrative and not restrictive.

What is claimed is:

I. A spring insulator for mounting machines, particularly fans, ventilators, blowers and the like, in a vibration and sound insulating manner, said insulator comprising a lower pot-shaped member having an upper open end and a lower closed end adapted to be fixed to a floor; an upper pot-shaped member having a lower open end and an upper closed end adapted to be connected to a machine to be mounted, each of said members having a peripheral wall, one of which surrounds the other with ample clearance; at least one compression spring abutting with opposite ends against the closed ends of said members so as to hold said members axially out of contact with each other, said spring being surrounded by the peripheral walls of said members spaced with ample clearance therefrom; and at least one flexible connecting element connected at opposite ends to said upper and lower member, respectively, said connecting element having a length such that when said insulator is not loaded, said connecting element is stressed and said spring maintained in pre-stressed condition, and said connecting element being relieved of its stress and hanging loosely after application of a load to said upper part, said spring and said connecting element forming the only connection between said upper and said lower member.

2. A spring insulator as defined in claim I, wherein said compression spring is a helical steel compression spring.

3. A spring insulator as defined in claim 1, wherein the peripheral wall of said upper member partly surrounds the peripheral wall of said lower member.

4. A spring insulator as defined in claim 3, wherein said lower member has an annular flange radially projecting from the closed lower end thereof, wherein the peripheral wall of each of said members has a free end edge, and wherein said compression spring is constructed to maintain, during loading of said insulator with a maximum permissible load, the end edge of the peripheral wall of said upper member out of contact with said flange and the end edge of the peripheral wall of said lower member out of contact with said closed end of said upper member.

5. A spring insulator as defined in claim 2, wherein only one flexible connecting element is provided for each helical compression spring and is arranged coaxially with said helical compression spring passing through the center of the latter.

6. A-spring insulator as defined in claim 1, wherein said connecting element consists of a metal chain.

7. A spring insulator as defined in claim 6, wherein said metal chain is constituted by a welded link-type chain of steel.

8. A spring insulator as defined in claim 1, wherein said connecting element consists of a cable,

9. A spring insulator as defined in claim 8, wherein said cable is a steel cable.

10. A spring insulator as defined in claim 1, wherein said connecting element is made of plastic.

11. A spring insulator as defined in claim 1, wherein said connecting element is detachably affixed to at least one of said members.

12. A spring insulator as defined in claim 1, and including a mounting and guiding ring sandwiched between at least one end of said spring and the closed end of the corresponding member, said ring being made from a material having sound damping properties.

13. A spring insulator as defined in claim 12, wherein said material of said ring is taken from the group of materials consisting of rubber and plastics.

14. A spring insulator as defined in claim 1, wherein at least one of said members is provided with a device for adjusting the height of the bearing surface of the insulator.

15. A spring insulator as defined in claim 1, wherein at least one of said members consists of an oil-petrolacid resisting synthetic material having a considerably tenacity and being resistant to abrasion. 

1. A spring insulator for mounting machines, particularly fans, ventilators, blowers and the like, in a vibration and sound insulating manner, said insulator comprising a lower pot-shaped member having an upper open end and a lower closed end adapted to be fixed to a floor; an upper pot-shaped member having a lower open end and an upper closed end adapted to be connected to a machine to be mounted, each of said members having a peripheral wall, one of which surrounds the other with ample clearance; at least one compression spring abutting with opposite ends against the closed ends of said members so as to hold said members axially out of contact with each other, said spring being surrounded by the peripheral walls of said members spaced with ample clearance therefrom; and at least one flexible connecting element connected at opposite ends to said upper and lower member, respectively, said connecting element having a length such that when said insulator is not loaded, said connecting element is stressed and said spring maintained in pre-stressed condition, and said connecting element being relieved of its stress and hanging loosely after application of a load to said upper part, said spring and said connecting element forming the only connection between said upper and said lower member.
 2. A spring insulator as defined in claim 1, wherein said compression spring is a helical steel compression spring.
 3. A spring insulator as defined in claim 1, wherein the peripheral wall of said upper member partly surrounds the peripheral wall of said lower member.
 4. A spring insulator as defined in claim 3, wherein said lower member has an annular flange radially projecting from the closed lower end thereof, wherein the peripheral wall of each of said members has a free end edge, and wherein said compression spring is constructed to maintain, during loading of said insulator with a maximum permissible load, the end edge of the peripheral wall of said upper member out of contact with said flange and the end edge of the peripheral wall of said lower member out of contact with said closed end of said upper member.
 5. A spring insulator as defined in claim 2, wherein only one flexible connecting element is provided for each helical compression spring and is arranged coaxially with said helical compression spring passing through the center of the latter.
 6. A spring insulator as defined in claim 1, wherein said connecting element consists of a metal chain.
 7. A spring insulator as defined in claim 6, wherein said metal chain is constituted by a welded link-type chain of steel.
 8. A spring insulator as defined in claim 1, wherein said connecting element consists of a cable.
 9. A spring insulator as defined in claim 8, wherein said cable is a steel cable.
 10. A spring insulator as defined in claim 1, wherein said connecting element is made of plastic.
 11. A spring insulator as defined in claim 1, wherein said connecting element is detachably affixed to at least one of said members.
 12. A spring insulator as defined in claim 1, and including a mounting and guiding ring sandwiched between at least one end of said spring and the closed end of the corresponding member, said ring being made from a material having sound damping properties.
 13. A spring insulator as defined in claim 12, wherein said material of said ring is taken from the group of materials consisting of rubber and plastics.
 14. A spring insulator as defined in claim 1, wherein at least one of said members is provided with a device for adjusting the height of the bearing surface of the insulator.
 15. A spring insulator as defined in claim 1, wherein at least one of said members consists of an oil-petrol-acid resisting synthetic material having a considerably tenacity and being resistant to abrasion. 